Question 414662
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Hi
sum of the digits in a certain two-digit number is 12
Let x and (12-x)represent the unit and ten's digit respectively
Question states***  Note: [10(12-x)+ x] is the original number
  10x + (12-x) = [10(12-x)+ x] + 18
       18x = 126   
         x = 7, the unit's digit, the ten's digit is 5, the number 57.

CHECKING our Answer***
75 = 57 + 18